Which Chinese dynasty invented gunpowder?

The Tang, in the ninth century, and it was found by alchemists looking for an elixir of immortality - a formula for eternal life that turned out to explode. One text of the period warns practitioners that mixing sulphur, saltpetre and charcoal has burned down buildings and injured people, which is the earliest known written safety notice about it.

Weapons followed under the Song, and they were more inventive than the standard account suggests: fire lances, exploding bombs thrown by catapult, and rockets, several centuries before cannon reached Europe. The knowledge travelled west, probably via the Mongols, and Europe's contribution was largely metallurgical - casting barrels able to contain the pressure.

The old claim that China invented gunpowder and used it only for fireworks is wrong and is worth retiring. Chinese armies used it in warfare extensively for centuries. What differed was context: Europe was a set of small competing states in constant war, which drove artillery development at a pace a large unified empire facing steppe cavalry had less reason to match.